Gas Boiler, recent soot, and 2 flame rollout switches

optimist55116

I have no heat! On Sunday I went down to the 12 year old Burnham gas boiler to find it was down.

Here is the background:

1. Burnham 205H (130K) gas boiler 12-13 years old, no problem since we've been in the house. Old 1930's house in with addition totals about 3200 sq ft, St Paul, MN. Boiler area open to 1000 sq ft basement (no door). Also a 42K water heater in same area (common vent).

2. fresh air intake: 6 in round galvanized from outside to 15 gal bucket.

3. CO detector in basement and upstairs.

4. I am finishing basement. Sawdust, and drywall dust.

5. November I had to replace the B-vent going to boiler (Pretty much 15 ft straight down from rain cap). When I was pulling old sections up, a bunch of loose cellulose insulation fell straight into boiler hood. The automatic damper was closed and I thought I got it all. (Maybe!)

Here and Now:
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6. Flame rollout switch popped on Sunday. I pull off the vent and see recent and rather dramatic layer of soot (1/32 - 1/16 inch) on heat exchangers. This was all new, since November. Even some larger curls of soot in tray under burners.

7. I pull all burners, clean them with brush and blow them out. I use compressed air to blow off soot from heat
exchangers, vacuum everywhere I can, and put things back together.

8. I also look up vent to rain cap. No blockage, but layer of black soot all the way up.

9. I order two new FRS, put one in tonight and, fire up boiler. I even open a window in the basement first, and put a CO
detector I trust within 6 feet of boiler. It ignites normally, but the flame is a sickly yellow-blue. I let it run to see if it clears up.

After about 15 minutes, no change in color and no rising CO, but the front of boiler is way warmer than it should be. As I pull it off, the FRS pops again.

I'm still trying to get someone to come out and take a look without paying for an 'emergency visit'. The weather is mild, but we're running out of time.
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I know the post is long, but I tried to cover all the bases. Any good guesses? Oh yeah, some pics: not great since I haven't taken the canopy off.

Steamhead

Call a pro first thing in the morning, and do not run the boiler until it's fixed. Something is seriously wrong here.

Lance

Steamhead is right. You need a pro. First a draft reading should be done to determine what is going on between the flue and the fire. Second a manifold gas pressure check for firing rate. Possible problems are, flue pipe not drawing due to air leak or negative air pressure in building. Under the flue collector in the boiler, which needs to be removed, a visual check for blockage can be performed. Good possibility problem is here since you had the insulation drop. Possible over gassing of the fire rate, failure of gas valve pressure control. When all is corrected you should get a combustion test done, and keep the record on file.
15' for a flue is bare minimum for a chimney height. Also did anything else change in the building? And what is the actual fresh air makeup? Don't discount a boiler leak impinging water onto a burner. Leaks come and go depending on corrosion and metal expansion / contraction. Some only leak when hot and stop when cooled down. On rare occasions a couple of things can be going on at the same time. Lance

optimist55116

<Response to Steamhead>
No kidding!? I know you felt compelled to say that, but I would hope, even from my write-up, you would sense we both knew that. The only time it has been started up since Sunday was 10 to 15 min last night.

Someone is scheduled to come out, but not until Tuesday. I'm only trying to cover the things I feel competent to check or clean. About the only remaining thing I feel able to do is clean the heat exchangers, but I'm trying to assess the probability that is the proble

optimist55116

Update: While I waited for the person to come out, I pulled out the burners again and took some pictures. Here is one of the scarier ones.

The interesting thing--to me at least--is how localized the soot is, especially for how much build-up there is. The center three sections look like they were invaded by the carbon blob from another planet.

What I cut out from my first, long post, was that my replacement of the B-vent stack was because the I noticed that the rain cap blew off. Could water dropping on the center sections cause soot to form (like a cracked and leaking exchanger)?

I spent Saturday and part of Sunday with wire brushes, air, and a vacuum cleaner going at it from both top and bottom.

I finished by replacing the last 36 inches of the single wall to the hood with B-vent, just in case. (Heck, I was trying to get an exorcist over here.) And then I swapped in the last FRS and ...
nothing!

I didn't even try to fire it up. Like I said, I wasn't going to fire it up again without a combustion analysis--and somebody who knew how to do one. I was trying to do what I could to save money.

The person came today, we fired it up, he said the flame looks fine and he hooked up the analyzer. The brief printout ( customer version) says 3.6 % CO2, 14.6% O2 and 2 ppm CO (7 ppm undiluted), and 82.7% efficiency.

He wondered about 199% excess air (looked at his other recent test and said it was similar to other units in this class. I was concern about the stack temp of 210.5F (12-15 minutes after startup), but I have a large buffer tank that wasn't even close to 100F yet.

So he said everything seems OK. I just need the rest of this season, as I'm getting at least a direct vent this summer.

Steamhead

3.6% CO2 and a stack temp of 210.5° F is not normal. Get a second opinion.

optimist55116

Since i just paid a professional a bunch of money to come out (after vetting him as much as I could) and you're suggesting I sign over the remainder of this pay check, could you give me a hint as to what isn't right, or at least a reference so I can do my own research and figure out what to do.

(Sorry about being acerbic.) I just went a week without heat, and this whole "have a professional look at it" is getting thin. And I'm going to explain to my wife that the money spent is wasted.

vaporvac

Where are you located?

captainco

Either the guy that did the combustion test took it in the wrong place(most likely) which means he doesn't know how to do it, or your boiler is really messed up. The combustion numbers equate to a real efficiency below 50%. I feel sorry for this guys other customers if this is all he knows.

Fred

Don't let the advise rub you thin. When Steamhead tells you the numbers aren't normal, trust that and get someone who knows what they are doing and where to take the measurements. Despite all of our best efforts, sometimes we all make a mistake in selecting "the right" technician. When that happens, we have to bite the bullet and start over. The money spent, sometimes, has to be chalked up as the cost of a learning experience. Not much consolation but , at the end of the day, you want it right and safe.